Most 'Auto focus' you found on some advertisement is not really a true 'auto' but semi-auto focus system . They do not has a real time tracking capabilities .

With our real time auto focusing (RTAF) system, the motorized laser head will trace curve object and make self adjustment for the focus point while running a job. It works great for non-metal materials cutting in a condition that the object is either semi-transparent or non-transparent. It won't works well on object with full transparency like acrylic!